This invention relates to a system for locking an overhead sunshade in an open or closed position while allowing it to slide relatively freely during movement. The improved system further includes a mechanism for engaging and opening the overhead sunshade when the corresponding overhead window is opened.
It is common for modern vehicles to be equipped with a xe2x80x9cmoon roofxe2x80x9d in the ceiling of the cab of the vehicle. Generally, the xe2x80x9cmoon roofxe2x80x9d consists of a slidable glass window in the roof of the vehicle and a corresponding slidable sunshade in the cab interior which may cover the window. During operation, the sunshade may be opened completely or partially, with the window closed, to allow the desired inflow of day or night light. Alternatively, the window and sunshade may both be partially or completely opened to allow an inflow of fresh air as well as light.
Typically, the window and the sunshade open from the front to the back of the vehicle. Window movement is powered by a motor controlled by the vehicle operator. The sunshade is typically manually moved by the vehicle operator, although the window is moved to open, it opens the sunshade.
During vehicle operation, it is desirable that the sunshade remains in the position to which it has been moved and does not slide freely when the vehicle undergoes acceleration or braking. As an example, if the sunshade is open and the vehicle is suddenly stopped, the force on the sunshade tends to close the sunshade. To resist this force, the sunshade is mounted with a significant degree of frictional contact between the side edges of the sunshade and the side tracks within which it slides. This frictional contact resists the forces imposed upon the sunshade during vehicle acceleration or braking. However, this frictional contact sometimes results in a sunshade that is difficult or awkward to manually operate by the driver, that is the force to move the sunshade must overcome this frictional force, and thus the force is sometimes undesirably high.
It would be desirable to provide a slidable sunshade with a mechanism that would reduce or disable the frictional contact between the side edges of the sunshade and the side tracks within which it slides during manual sliding.
In the disclosed embodiment of this invention, a sunshade is provided with a spring biased cam locking system that may reduce the frictional contact between the side edges of the sunshade and the side tracks within which it slides when the vehicle operator manually slides the sunshade to an open or closed position. This allows smooth and easy operation of the sunshade by the vehicle operator while providing high frictional contact once the sunshade is positioned as desired. Thus, the sunshade, once positioned, does not uncontrollably slide open or closed in response to forces imposed by vehicle acceleration and braking.
Although a particular embodiment of the locking system is disclosed, it should be understood that this application extends to many distinct locking systems. The disclosed system is merely an example of one which can provide the inventive goals and features.
The spring-biased cam locking system includes a cross bar that extends across the width of the sunshade. The width, in this case, refers to the direction from side to side of the vehicle. The cross bar is separated into two segments at its midpoint providing an inner end surface on each cross bar segment that slides along respective opposing surfaces of a cam element positioned between the cross bar segments. The outermost, or extreme, ends of the cross bar segment frictionally and slidably interfit in the side tracks within which the sunshade slides. The cam element is provided with forward and rearward extensions and a frontwardly extending pull tab for manually pulling or sliding the sunshade closed and open.
Each cross bar segment is provided with a spring element which biases each cross bar segment toward each respective cam element surface. The cam element is provided with a pair of equalizing spring elements that work together. The cam element is symmetrical and has opposing operative surfaces that work with the inner end surface of each of the two cross bar segments. The opposing operative surfaces of the cam element comprise an opposing pair of frontward recesses and an opposing pair of rearward recesses separated by an opposing pair of laterally extending protuberances, each containing a small notch. The inner end surface of each cross bar segment is designed to interfit with both pairs of recesses as well as the pair of small notches.
At rest, the tensile and compressive forces on the pair of spring elements in the cam element are equalized. The inner end surface of each cross bar segment is received by each of the pair of small notches in each laterally extending protuberance, thus pushing each cross bar segment in opposing directions so that the outermost ends of the cross bar segments are frictionally engaged in the side tracks of the sunshade. Thus, the sunshade is frictionally locked into position.
Alternatively, when the sunshade is manually moved by a vehicle operator using the frontwardly extending pull tab, the inner end surface of each cross bar segment is received by either the rearward or frontward pair of recesses thus allowing the cross bar segments to be biased inwardly. Hence, the outermost ends of the cross bar segments are no longer frictionally received within the side tracks of the sunshade and frictional contact is thus reduced.
Further, as will be disclosed below, the locking system is released during the automatic movement of the window to an open position.
During the forward or rearward movement of the sunshade, the tensile and compressive forces in the pair of spring elements in the cam element are no longer equal. Once movement is halted, however, the spring elements in the cam element equalize their tensile and compressive forces, resulting in forward or rearward movement of the cam element which, in turn, causes the laterally extending protuberances to push the cross bar segments outward from each other until their inner end surfaces engage the pair of small notches and the outermost ends of the cross bar segments are once again frictionally engaged within the side tracks of the sunshade.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.